A chest x-ray of a patient with nitrogen oxide poisoning shows corn-like shadows all over both lungs. Nitrogen oxides (nitrogen oxides) include a variety of compounds, such as nitrous oxide (N2O), nitric oxide (N0), nitrogen dioxide (NO2), nitrous oxide (N203), nitrous oxide (N204) and nitrous oxide (N205). In addition to nitrogen dioxide, all other nitrogen oxides are extremely unstable and become nitrogen dioxide and nitric oxide when exposed to light, moisture or heat, and nitric oxide becomes nitrogen dioxide. Therefore, the occupational environment is exposed to a mixture of several gases often called nitrous fumes (gas), mainly nitrogen oxide and nitrogen dioxide, and mainly nitrogen dioxide. 1, acute mild poisoning Generally, after a few hours to 72h incubation period of nitrogen oxide inhalation, chest tightness, coughing, coughing, etc., accompanied by mild headache, dizziness, weakness, palpitations, nausea, fever and other symptoms; conjunctiva and nasopharynx mild congestion and scattered dry rales in the lungs. Chest X-ray showed enhanced lung texture or blurred lung texture margins. Blood gas analysis: when breathing air, the partial pressure of arterial blood oxygen may be lower than the expected value of 1,33~2,66kPa (l0~2OmmHg). 2.Acute moderate poisoning There is dyspnea, chest urgency, increased cough, coughing sputum or coughing blood sputum, often accompanied by dizziness, headache, weakness, palpitation, nausea and other symptoms, and mild cyanosis. There are dry rales or scattered wet rales in both lungs. Total blood leukocyte count is elevated. Chest X-ray shows decreased lung field translucency, increased, disorganized and blurred lung texture in the form of reticular shadows; or there are localized or scattered dotted shadows, or they fuse with each other to form patchy shadows with blurred edges. Blood gas analysis: The partial pressure of arterial blood oxygen can be maintained at greater than 8 kPa (6OmmHg) only when low concentration of oxygen is inhaled (less than 50%). 3.Acute severe poisoning Those who show one of the following clinical manifestations are considered severe poisoning. (1) Pulmonary edema, respiratory distress, increased cough, coughing up large amounts of white or pink foamy sputum, and obvious cyanosis. Both lungs can be heard as dry and wet? sound. Chest X-ray shows that the two lungs are covered with low density, blurred patchy shadows or cloudy shadows of different sizes, and some of them fuse with each other to form a large patchy shadow. Complications such as pneumothorax and mediastinal emphysema may be present. Blood gas analysis: arterial partial pressure of oxygen is less than 8 kPa (60 mmHg) in the presence of high oxygen inhalation (>50%). (2) Coma or asphyxia. (3) Acute respiratory distress syndrome (ARDS). (4) Delayed obstructive capillary bronchitis occurs suddenly with cough, chest tightness, progressive dyspnea and marked cyanosis after inhalation of nitrogen oxide gas without obvious acute toxic symptoms or about 2 weeks after the recovery phase of pulmonary edema. Dry and wet rales or fine wet rales can be heard in both lungs. A chest X-ray shows corn-like shadows all over the two lungs. Long-term exposure to low concentrations (above the maximum allowable concentration) of nitrogen oxides can cause bronchitis and emphysema.